A two-phase three-wire type is a power feeding type in which a two-phase alternating-current (AC) voltage and a neutral point voltage are fed to consumers. In Japan, the phases of the two-phase AC voltage are shifted by 180 degrees from each other, which is referred to as a single-phase three-wire type. An AC voltage in one phase of the two-phase AC voltage and a neutral point voltage are supplied to an electrical device of 100V A two-phase AC voltage is supplied to an electrical device of 200V In North America, a two-phase AC voltage of the three-phase AC voltage is supplied to consumers, and the phases of the two-phase AC voltage are shifted by 120 degrees from each other.
Japanese Patent Laying-Open No. 06-253549 (PTD 1) discloses an uninterruptible power supply device of a single-phase three-wire type. This uninterruptible power supply device includes: a converter configured to convert a two-phase AC voltage supplied from a commercial AC power supply into a direct-current (DC) voltage; and an inverter configured to convert the DC voltage generated by the converter or a DC voltage from a power storage device into a two-phase AC voltage and supply the converted two-phase AC voltage to a load.